A Catalog of ^(13)CO Clumps from the MWISP in l=10°–20°

In this study, we present a catalog of molecular clumps extracted from ^(13)CO(J=1-0) emission data of the Milky Way Imaging Scroll Painting(MWISP) project. The data covers the inner Milky Way within the longitude range10°≤l≤20° and the latitude strip of |b|≤ 5°. 25. The workflow for the extraction of clumps, namely Facet-SS-3DClump, consists of two parts: the identification of clump candidates and their verification. First, Facet-SS-3DClump employs FacetClumps to identify clump candidates. Subsequently, high-confidence clumps are obtained by cross-matching with the clumps detected by other algorithms, such as dendrogram. Second, these high-confidence clumps are used as prior knowledge to train a semi-supervised deep clustering approach, SS-3D-Clump, which is applied to verify clump candidates detected by FacetClumps, providing confidence levels for the molecular clumps. Finally, the catalog comprising 18,757 molecular clumps was obtained using Facet-SS-3D-Clump, and the catalog is 90% complete above 37 K km s^(-1). We observe a significant deviation of the mean Galactic latitude for clumps within |b|≤ 2° from the midplane, with b=-0°.110. We found that 82.3% of the dust clumps correspond to ^(13)CO clumps by matching with Herschel infrared dust clumps. In the future, Facet-SS-3D-Clump will be applied to detect ^(13)CO clumps in the entire MWISP data.

Transverse momentum balance of dijets in Xe+Xe collisions at the LHC

We present a theoretical study of the medium modifications of the p_(T)balance (x_(J)) of dijets in Xe+Xe collisions at■.The initial production of dijets was carried out using the POWHEG+PYTHIA8 prescription,which matches the next-toleading-order (NLO) QCD matrix elements with the parton shower (PS) effect.The SHELL model described the in-medium evolution of nucleus–nucleus collisions using a transport approach.The theoretical results of the dijet xJin the Xe+Xe collisions exhibit more imbalanced distributions than those in the p+p collisions,consistent with recently reported ATLAS data.By utilizing the Interleaved Flavor Neutralisation,an infrared-and-collinear-safe jet flavor algorithm,to identify the flavor of the reconstructed jets,we classify dijets processes into three categories:gluon–gluon (gg),quark–gluon (qg),and quark–quark (qq),and investigated the respective medium modification patterns and fraction changes of the gg,qg,and qq components of the dijet sample in Xe+Xe collisions.It is shown that the increased fraction of qg component at a small x_(J)contributes to the imbalance of the dijet;in particular,the q_(1)g_(2)(quark-jet-leading) dijets experience more significant asymmetric energy loss than the g_(1)q_(2)(gluon-jet-leading) dijets traversing the QGP.By comparing the■of inclusive,■ dijets in Xe+Xe collisions,we observe■.Moreover,ρ_(Xe),P_(b),the ratios of the nuclear modification factors of dijets in Xe+Xe to those in Pb+Pb,were calculated,which indicates that the yield suppression of dijets in Pb+Pb is more pronounced than that in Xe+Xe owing to the larger radius of the lead nucleus.

Probing the Galactic Halo with RR Lyrae Stars.VI.The Radial Velocity Curve Templates of RRc Stars

We present radial velocity(RV)curve templates of RR Lyrae first-overtone(RRc)stars constructed with the Mg I b triplet and Hαlines using time-domain Medium-Resolution Survey spectra of seven RRc stars from Large Sky Area Multi-Object Fiber Spectroscopic Telescope(LAMOST)Data Release 9.Additionally,we derive the relation between the stellar RV curve amplitudes and g-band light curve amplitudes from Zwicky Transient Facility(ZTF)public survey.For those RRc stars without ZTF g-band light curves,we provide the conversions from the light curve amplitudes in ZTF r-and i-bands,Gaia G-band,and V-band from the All-Sky Automated Survey for Supernovae to those in ZTF g-band.We validate our RV curve templates using the RRc star SV Scl and find the uncertainties of systemic RV are less than 2.11 km s~(-1)and 6.08 km s~(-1)based on the Mg I b triplet and Hαlines,respectively.We calculate the systemic RVs of 30 RRc stars using the RV curve templates constructed with the Mg I b triplet and Hαlines and find the systemic RVs are comparable with each other.This RV curve template will be particularly useful for obtaining the systemic RV of RRc using the LAMOST spectroscopy.

The electrical design of a membrane antenna for a lunar-based low-frequency radio telescope

Detecting primordial fluctuations from the cosmic dark ages requires extremely large low-frequency radio telescope arrays deployed on the far side of the Moon.The antenna of such an array must be lightweight,easily storable and transportable,deployable on a large scale,durable,and capable of good electrical performance.A membrane antenna is an excellent candidate to meet these criteria.We study the design of a low-frequency membrane antenna for a lunar-based low-frequency(<30 MHz)radio telescope constructed from polyimide film widely used in aerospace applications,owing to its excellent dielectric properties and high stability as a substrate material.We first design and optimize an antenna in free space through dipole deformation and coupling principles,then simulate an antenna on the lunar surface with a simple lunar soil model,yielding an efficiency greater than 90%in the range of 12-19 MHz and greater than 10%in the range of 5-35 MHz.The antenna inherits the omni-directional radiation pattern of a simple dipole antenna in the 5-30 MHz frequency band,giving a large field of view and allowing detection of the 21 cm global signal when used alone.A demonstration prototype is constructed,and its measured electrical property is found to be consistent with simulated results using|S11|measurements.This membrane antenna can potentially fulfill the requirements of a lunar low-frequency array,establishing a solid technical foundation for future large-scale arrays for exploring the cosmic dark ages.

In search of infall motion in molecular clumpsⅡ:HCO+(1-0)and HCN(1-0)observations toward a sub-sample of infall candidates

Gravitational accretion accumulates the original mass.This process is crucial for us to understand the initial phases of star formation.Using the specific infall profiles in optically thick and thin lines,we searched the clumps with infall motion from the Milky Way Imaging Scroll Painting(MWISP)CO data in previous work.In this study,we selected 133 sources as a sub-sample for further research and identification.The excitation temperatures of these sources are between 7.0 and 38.5 K,while the H2 column densities are between 10^21 and 10^23 cm^-2.We have observed optically thick lines HCO+(1-0)and HCN(1-0)using the DLH 13.7-m telescope,and found 56 sources with a blue profile and no red profile in these two lines,which are likely to have infall motions,with a detection rate of 42%.This suggests that using CO data to restrict the sample can effectively improve the infall detection rate.Among these confirmed infall sources are 43 associated with Class O/I young stellar objects(YSOs),and 13 which are not.These 13 sources are probably associated with the sources in the earlier evolutionary stage.In comparison,the confirmed sources that are associated with Class O/I YSOs have higher excitation temperatures and column densities,while the other sources are colder and have lower column densities.Most infall velocities of the sources that we confirmed are between 10^-1 to 10^0 km s^-1,which is consistent with previous studies.

A Catalog of Molecular Clumps and Cores with Infall Signatures

The research of infall motion is a common means to study molecular cloud dynamics and the early process of star formation. Many works had been done in-depth research on infall. We searched the literature related to infall study of molecular cloud since 1994, summarized the infall sources identified by the authors. A total of 456 infall sources are cataloged. We classify them into high-mass and low-mass sources, in which the high-mass sources are divided into three evolutionary stages: prestellar, protostellar and H II region. We divide the sources into clumps and cores according to their sizes. The H2 column density values range from 1.21 × 10^(21) to 9.75 × 10^(24) cm^(-2), with a median value of 4.17 × 10^(22) cm^(-2). The H_(2) column densities of high-mass and low-mass sources are significantly separated. The median value of infall velocity for high-mass clumps is 1.12 km s^(-1), and the infall velocities of lowmass cores are virtually all less than 0.5 km s^(-1). There is no obvious difference between different stages of evolution. The mass infall rates of low-mass cores are between 10^(-7) and 10^(-4) M⊙yr^(-1), and those of high-mass clumps are between 10^(-4 )and 10-1 M⊙yr^(-1) with only one exception. We do not find that the mass infall rates vary with evolutionary stages.

Chinese Sunspot Drawings and Their Digitization—(Ⅶ) Sunspot Penumbra to Umbra Area Ratio Using the Hand-Drawing Records from Yunnan Observatories

The ratio of penumbral to umbra area of sunspots plays a crucial role in the solar physics fields, especially for understanding the origin and evolution of the solar activity cycle. By analyzing the recently digitized sunspot drawings observed from Yunnan Observatories(1957–2021), we investigate the long-term variation of the penumbral to umbra area ratio of sunspots. An automatic extraction method, based on the maximum between-class variance and the morphological discrimination, is used to accurately extract penumbra and umbra and to calculate the ratio over six solar cycles(cycle 19–24). The expected value of the ratio of penumbra to umbra area is found to be 6.63 ± 0.98, and it does not exhibit any systematic variation with sunspot latitudes and phases. The average ratio fluctuates from 5 to 7.5 per year and the overall trend has decreased after 1999 compared to the previous one.The ratio of sunspot penumbra to umbra area satisfies the log-normal distribution, implying that its variation is related to the evolution of the photospheric magnetic field. Our results are consistent with previous works.

Erratum:“In Search for Infall Motion in molecular clumps Ⅱ:HCO+(1-0)and HCN(1_0)Observations toward a Sub-sample of Infall Candidates”(2020,RAA,20,115)

In the paper“In Search for Infall Motion in molecular clumps II:HCO+(1-0)and HCN(1-0)Observations toward a Sub-sample of Infall Candidates”by Yang etal.(RAA 2020 Vol.20 No.8,115(14pp),doi:10.1088/1674C4527/20/8/115),the formula(4)is incorrectly reproduced from Myers et al.(1996).

Variable Star Detection in the Field of Open Cluster NGC 188

This work presents the charge-coupled device(CCD)photometric survey of the old open cluster NGC 188.Timeseries V-band photometric observations were conducted for ten nights in 2017 January using the Nanshan Onemeter Wide-field Telescope to search for variable stars in the field of the cluster.A total of 25 variable stars,including one new variable star,were detected in the target field.Among the detected variables,16 are cluster member stars,and the others are identified as field stars.The periods,radial velocities,effective temperatures,and classifications of the detected variables are discussed in this work.Most of the stars’effective temperatures are between 4200 and 6600 K,indicating their spectral types are G or K.The newly discovered variable is probably a W UMa system.In this study,a known cluster variable star(V21=V0769 Cep)is classified as an EA-type variable star based on the presence of an 0.5 mag eclipse in its light curve.

In Search for Infall Gas in Molecular Clouds:A Catalogue of CO Blue-Profiles

We have started a systematic survey of molecular clumps with infall motions to study the very early phase of star formation.Our first step is to utilize the data products by MWISP to make an unbiased survey for blue asymmetric line profiles of CO isotopical molecules.Within a total area of~2400 square degrees nearby the Galactic plane,we have found 3533 candidates showing blue-profiles,in which 3329 are selected from the^(12)CO&^(13)CO pair and 204 are from the^(13)CO&C^(18)O pair.Exploration of the parametric spaces suggests our samples are in the cold phase with relatively high column densities ready for star formation.Analysis of the spatial distribution of our samples suggests that they exist virtually in all major components of the galaxy.The vertical distribution suggest that the sources are located mainly in the thick disk of~85 pc,but still a small part are located far beyond Galactic midplane.Our follow-up observation indicates that these candidates are a good sample to start a search for infall motions,and to study the condition of very early phase of star formation.

ISMGCC:Finding Gas Structures in Molecular Interstellar Medium Using Gaussian Decomposition and Graph Theory

Molecular line emissions are commonly used to trace the distribution and properties of molecular Interstella Medium.However,the emissions are heavily blended on the Galactic disk toward the inner Galaxy because of th relatively large line widths and the velocity overlaps of spiral arms.Structure identification methods based on voxe connectivity in Position-Position-Velocity(PPV)data cubes often produce unrealistically large structures,which i the“over-linking”problem.Therefore,identifying molecular cloud structures in these directions is not trivial.W propose a new method based on Gaussian decomposition and graph theory to solve the over-linking problem named InterStellar Medium Gaussian Component Clustering(ISMGCC).Using the Milky Way Imaging Scrol Painting(MWISP)^(13)CO(1-0)data in the range of 13°.5≤l≤14°.5,|b|≤0°.5,and-100≤V_(lsr)≤+200 km s^(-1),our method identified three hundred molecular gas structures with at least 16 pixels.These structures contain 92%of the total flux in the raw data cube and show single-peaked line profiles on more than 93%of their pixels.Th ISMGCC method could distinguish gas structures in crowded regions and retain most of the flux without globa data clipping or assumptions on the structure geometry,meanwhile,allowing multiple Gaussian components fo complicated line profiles.

Molecular Clump Extraction Algorithm Based on Local Density Clustering

The detection and parameterization of molecular clumps are the first step in studying them.We propose a method based on the Local Density Clustering algorithm while physical parameters of those clumps are measured using the Multiple Gaussian Model algorithm.One advantage of applying the Local Density Clustering to the clump detection and segmentation,is the high accuracy under different signal-to-noise levels.The Multiple Gaussian Model is able to deal with overlapping clumps whose parameters can reliably be derived.Using simulation and synthetic data,we have verified that the proposed algorithm could accurately characterize the morphology and flux of molecular clumps.The total flux recovery rate in 13CO(J=1-0)line of M16 is measured as 90.2%.The detection rate and the completeness limit are 81.7%and 20 K km s-1 in 13CO(J=1-0)line of M16,respectively.

A new comprehensive dataset of solar filaments of one-hundred-year interval (Ⅱ) the poleward migration of polar crown filaments

Solar filaments,hypothermia and dense structures suspended in the solar corona are formed above the magnetic polarity inversion line.Polar crown filaments(PCFs)at high-latitude regions of the Sun are of profound significance to the periodic variation of solar activities.In this paper,we statistically analyze PCFs by using full disk Ha data from 1912 to 2018,which were obtained by Kodaikanal Solar Observatory(KODA,India),National Solar Observatory(NSO,USA),Kanzelhohe Solar Observatory(KSO,Austria),Big Bear Solar Observatory(BBSO,USA),and Huairou Solar Observing Station(HSOS,China).We first manually identify PCFs from every solar image based on the centennial data,and record the latitude and other features corresponding to the PCFs.Then we plot the PCF latitude distribution as a function of time,which clearly shows that PCFs rush to the poles at the ascending phase of each solar cycle.Our results show that the filaments drift toward mid-latitude covering solar cycle 15 to 24 after the PCFs reach the highest latitudes.The poleward migration rates of PCFs are calculated in ten solar cycles,and the range is about 0.12 degree to 0.50 degree per Carrington Rotation(CR).We also investigate the north-south(N-S)asymmetry of migration rates and the normalized N-S asymmetry index.

Preliminary analysis on the noise characteristics of MWISP data

Noise is a significant part within a millimeter-wave molecular line datacube.Analyzing the noise improves our understanding of noise characteristics,and further contributes to scientific discoveries.We measure the noise level of a single datacube from MWISP and perform statistical analyses.We identified major factors which increase the noise level of a single datacube,including bad channels,edge effects,baseline distortion and line contamination.Cleaning algorithms are applied to remove or reduce these noise components.As a result,we obtained the cleaned datacube in which noise follows a positively skewed normal distribution.We further analyzed the noise structure distribution of a 3 D mosaicked datacube in the range l=40°7 to 43°3 and b=-2°3 to 0°3 and found that noise in the final mosaicked datacube is mainly characterized by noise fluctuation among the cells.

Study of neutron density fluctuation and neutron-proton correlation in Au+Au collisions using PYTHIA8/Angantyr

Utilizing the PYTHIA8 Angantyr model,which incorporates the multiple-parton interaction(MPI)based color reconnection(CR)mechanism,we study the relative neutron density fluctuation and neutron-proton correlation in Au+Au collisions at√sNN=7.7,11.5,14.5,19.6,27,39,62.4,and 200 GeV.In this study,we not only delve into the dependence of these two remarkable observations on rapidity,centrality,and energy,but also analyze their interplay with the MPI and CR.Our results show that the light nuclei yield ratio of protons,deuterons,and tritons,expressed by the elegant expression N_(t)N_(p)/N^(d)^(2),remains unchanged even as the rapidity coverage and collision centrality increase.Interestingly,we also reveal that the effect of CR is entirely dependent on the presence of the MPI;CR has no impact on the yield ratio if the MPI is off.Our findings further demonstrate that the light nuclei yield ratio experiences a slight increase with increasing collision energy,as predicted by the PYTHIA8 Angantyr model;however,it cannot describe the non-monotonic trend observed by the STAR experiment.Based on the Angantyr model simulation results,it is essential not to overlook the correlation between neutron and proton fluctuations.The Angantyr model is a good baseline for studying collisions in the absence of a quark-gluon plasma system,given its lack of flow and jet quenching.

Systematic study of cluster radioactivity within the generalized liquid drop model

Cluster radioactivity is studied within the generalized liquid drop model(GLDM),in which the shell correction energy,pairing energy,and cluster preformation factor are considered.The calculations show significant improvements and can reproduce the experimental data within a factor of 8.04 after considering these physical effects.In addition,the systematic trend of the cluster preformation factors is discussed in terms of the N_(p)N_(n)scheme to study the influence of the valence proton-neutron interaction and shell effect on cluster radioactivity.It is found that log10Pcis linearly related to N_(p)N_(n).This is in agreement with a recent study[L.Qi et al.,Phys.Rev.C 108,014325(2023)],in which log10Pc,obtained using different theoretical models and treatment methods than those used in this study,also had a linear relationship with N_(p)N_(n).Combined with the work by Qi et al.,this study suggests that the linear relationship between log10Pcand N_(p)N_(n)is model-independent and both the shell effect and valence proton-neutron interaction play essential roles in cluster radioactivity.An analytical formula is proposed to calculate the cluster preformation factor based on the N_(p)N_(n)scheme.In addition,the cluster preformation factors and the cluster radioactivity half-lives of some heavy nuclei are predicted,which can provide a reference for future experiments.

The Tianlai Cylinder Pathfinder array: System functions and basic performance analysis

The Tianlai Cylinder Pathfinder is a radio interferometer array designed to test techniques for 21 cm intensity mapping in the post-reionization Universe,with the ultimate aim of mapping the large scale structure and measuring cosmological parameters such as the dark energy equation of state.Each of its three parallel cylinder reflectors is oriented in the north-south direction,and the array has a large field of view.As the Earth rotates,the northern sky is observed by drift scanning.The array is located in Hongliuxia,a radio-quiet site in Xinjiang,and saw its first light in September 2016.In this first data analysis paper for the Tianlai cylinder array,we discuss the sub-system qualification tests,and present basic system performance obtained from preliminary analysis of the commissioning observations during 2016-2018.We show typical interferometric visibility data,from which we derive the actual beam profile in the east-west direction and the frequency band-pass response.We describe also the calibration process to determine the complex gains for the array elements,either using bright astronomical point sources,or an artificial on site calibrator source,and discuss the instrument response stability,crucial for transit interferometry.Based on this analysis,we find a system temperature of about 90 K,and we also estimate the sensitivity of the array.

Revisiting the Velocity Dispersion-Size Relation in Molecular Cloud Structures

Structures in molecular ISM are observed to follow a power-law relation between the velocity dispersion and spatial size,known as Larson’s first relation,which is often attributed to the turbulent nature of molecular ISM and imprints the dynamics of molecular cloud structures.Using the^(13)CO(J=1-0)data from the Milky Way Imaging Scroll Painting survey,we built a sample with 360 structures having relatively accurate distances obtained from either the reddened background stars with Gaia parallaxes or associated maser parallaxes,spanning from 0.4 to~15 kpc.Using this sample and about 0.3 million pixels,we analyzed the correlations between velocity dispersion,surface/column density,and spatial scales.Our structure-wise results show power-law indices smaller than 0.5 in both theσ_(v)-R_(eff)andσ_(v)-R_(eff)·Σrelations.In the pixel-wise results,the v spix is statistically scaling with the beam physical size(R_(s)≡ΘD/2)in form ofσ_(v)^(pix)■R_(s)^(0.43±0.03).Meanwhile,σ_(v)_(pix)in the inner Galaxy is statistically larger than the outer side.We also analyzed correlations betweenσ_(v)_(pix)and the H_(2)column density N(H_(2)),finding thatσ_(v)_(pix)stops increasing with N(H_(2))after>10^(22)cm^(-2).The structures with and without high-column-density(>10^(22)cm^(-2))pixels show differentσ_(v)_(pix)■N(H_(2))^(ξ)relations,where the mean(std)ξvalues are 0.38(0.14)and 0.62(0.27),respectively.

Discovery of two rotational modulation periods from a young hierarchical triple system

GW Ori is a young hierarchical triple system located in λ Orionis, consisting of a binary(GW Ori A and B), a tertiary star(GW Ori C) and a rare circumtriple disk. Due to the limited data with poor accuracy, several short-period signals were detected in this system, but the values from diferent studies are not fully consistent. As one of the most successful transiting surveys, the transiting exoplanet survey satellite(TESS) provides an unprecedented opportunity to make a comprehensive periodic analysis of GW Ori. In this work we discover two significant modulation signals by analyzing the light curves of GW Ori's four observations from TESS, i.e.,(3.02 ± 0.15) and(1.92 ± 0.06) d, which are very likely to be the rotational periods caused by starspot modulation on the primary and secondary components, respectively. We calculate the inclinations of GW Ori A and B according to the two rotational periods. The results suggest that the rotational plane of GW Ori A and B and the orbital plane of the binary are almost coplanar. We also discuss the aperiodic features in the light curves;these may be related to unstable accretion. The light curves of GW Ori also include a third(possible) modulation signal with a period of(2.51±0.09) d, but the third is neither quite stable nor statistically significant.